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From: wf@dcs.gla.ac.uk (Bill Findlay)
Subject: Re: Type mess in Ada standard library
Date: 1999/07/22
Message-ID: <wf-2207991847030001@wyre.dcs.gla.ac.uk>#1/1
X-Deja-AN: 504090238
References: <7n1uu4$so8$1@pegasus.csx.cam.ac.uk> <7n32tt$cio$1@nnrp1.deja.com>
 <7n41v3$j6$1@pegasus.csx.cam.ac.uk> <7n5cp9$89b$1@nnrp1.deja.com>
Organization: The University of Glasgow
Newsgroups: comp.lang.ada
Date: 1999-07-22T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <7n5cp9$89b$1@nnrp1.deja.com>,
Robert Dewar <robert_dewar@my-deja.com> wrote:

> > |>   typ'Anonymous_Access
> 
> Just to be clear I would ONLY allow this in subprogram formals,
> and I would be quite happy to restrict it to those which had
> foreign conventions, otherwise I am afraid it would be horribly
> overused.
> 
...
> > Would it at the same time also be possible to add anonymous
> > arrays?
> >
> >   typ'Array(0..255,0..255)  -- anonymous 64k 2D array of typ
> >   typ'Array(<>,<>,<>)       -- any 3D array of typ
> 
> In fact it is *exactly* this question that makes me think that
> it is a bad idea to introduce the anonymous access type. If
> people simply think of this as a way to weaken typing (as in
> the above array proposal), rather than as a way to solve a
> particular problem in genericity at the interfacing level, I
> am afraid that such features can do more harm than good.
> 

I would much rather see Markus' anonymous array parameters in Ada than
the existing anonymous array types, which are a pitfall for beginners
yet add no new functionality.

The Standard Pascal conformant array feature does indeed apply
only at the level of (subprogram) interfacing, although complicated
proposals to apply the idea more broadly were eventually included
in Extended Pascal, essentially to provide Ada's unconstrained
array type functionality.

-- 
Bill Findlay
Department of Computing Science
The University of Glasgow